I’m going to sneak this one in at Zero: Know how to structure your data, graphs, formulas, code so that you can remember what the hell you were doing 2 months later, and so that others can comprehend too.

I’ve nevcer liked Custon Formats for timeExcel is inconsistant with its use of m which can bem – minutesmm – minutes with leading zerom – monthmm – month with leading zerommm – month name shortmmmm – month name